Method- Cream the butter and sugar until the resultant mixture is fluffy. Add the egg yolk and vanilla extract. Beat for a few seconds. Add the flour and baking powder. Lightly mix until incorporated. Cover and refrigerate the dough for 30 minutes.

Meanwhile, chop the pistachios. Once the dough has firmed up, make lime sized balls, dip in the egg white and coat with nuts. Place on a parchment lined baking sheet and press down with your fingers to make indentations.

Now, this is a classic Thumbprint cookie recipe and procedure except for the addition of baking powder. The baking powder gives a soft cake-y texture to the cookies and makes them rise. So if you find that the indentations you made before baking turn shallow, don’t panic. Just spread the jam on top.

Speaking of which, you can fill the centers with jam and then bake or vice versa. Filling jam after baking ensures that the cookies will not soften over time. Bake the cookies for about 12-15 minutes. Enjoy the results!